Istanbul , Turkey -LRB- CNN -RRB- -- A series of recent fires in at least five detention centers around the country has raised questions about living conditions in Turkey 's prison system .

Late Saturday night a fire broke out in the dormitory of a prison in the southeastern province of Sanliurfa . The fire claimed the lives of 13 prisoners and injured five others before authorities successfully extinguished the blaze .

Prisoners reportedly set fire to their mattresses to protest cramped and unsuitable living conditions .

A day after the first protest blaze was put out , prisoners in the same prison once again set fires in the dormitories , this time injuring 42 , according to the semi-official Anatolian Agency .

The latest prison fire occurred Tuesday in the southern province of Karaman . There were no casualties but inmates had to be evacuated to the prison yard . On Monday , similar fires were reported at other detention facilities , including prisons in Gaziantep , Adana and Osmaniye .

`` Overcrowding is the primary problem , '' said Ozturk Turkdogan , president of the Human Rights Foundation in Turkey , or IHD , pointing out that the Sanliurfa prison is equipped to house 375 prisoners but currently houses nearly 1,200 . The cell where the fire started was furnished with six beds but housed 18 prisoners , according to an IHD report .

`` When I was in the prison , at first we were six people in a six-person room , which was fine . But then , two by two they put more people in . Ultimately , we were 14 people living in the room , '' said Cemal Babaoglu , who spent three months in the prison last year awaiting trial .

Such overcrowding is not a new problem in Turkey , according to officials .

`` This is a problem that evolves from the past -LRB- but is -RRB- getting smaller as -LRB- we -RRB- head into the future . The steps that we have taken in order to minimize and eventually eliminate the problem are evident , '' said Justice Minister Sadullah Ergin at a press conference on Tuesday .

Turkey is in the process of upgrading its prison system and will increase its capacity nearly twofold by 2017 , according to officials .

The primary reason for overcrowding in Turkish prisons is a judicial system that errs on the side of detention rather than releasing the accused on bail before and during legal proceedings , and a new penal code that has lengthened prison sentences . According to the justice ministry , 27.5 % of prisoners are detainees awaiting the outcome of their trials .

But Turkdogan maintains that 41 % of all prisoners in Turkey are either awaiting trial or a decision from an appellate court , a situation made more problematic , he says , by the fact that over half of appealed convictions are eventually overturned .

According to Human Rights Watch researcher Emma Sinclair-Webb , it is not only the problem of overcrowding , which is present in many of the world 's penal systems , but also the lack of transparency that prevents prison conditions in Turkey from conforming to accepted international standards .

`` Human rights groups and -LRB- nongovernmental organizations -RRB- can not visit prisons easily without lengthy procedures , '' said Sinclair-Webb . `` Turkey lacks a regular system of independent monitors . ''

Experts who are in the best position to identify and prevent hazardous conditions are thus unable to make firsthand observations , reducing pressure that might otherwise accelerate improvements to basic necessities such as medical care and infrastructure .

`` The capacity to respond to these complaints , to take measures to prevent the kind of tragedy that happened at the -LRB- Sanliurfa -RRB- prison , we are not seeing at the moment , '' said Sinclair-Webb .

Sanliurfa prison has been in the headlines before . After his requests for a transfer were denied , an inmate who lit himself on fire in protest of living conditions died in July 2010 .

@highlight

A weekend fire at one prison in Turkey killed 13 inmates

@highlight

Prisoners reportedly set fire to their mattresses to protest living conditions

@highlight

An activist says the prison is nearly four times over its intended capacity

@highlight

Government officials say Turkey is upgrading its prison system